RENO, Nev. (AP) — A U.S. judge has ordered the government to revisit part of its environmental review of a lithium mine planned in Nevada, but denied opponents’ efforts to block it in a ruling the developer says clears the way for construction at the nation’s largest known deposit of the rare metal widely used in rechargeable batteries.

The ruling marks a significant victory for Canada-based Lithium Americas Corp. at its subsidiary’s project near Nevada’s border with Oregon, and a setback — at least for now — for conservationists, tribes and a Nevada rancher who have all been fighting it for two years. The opponents said they are considering an appeal based in part on growing questions raised about the reach of an 150-year-old mining law.

It’s the latest development in a series of high-stakes legal battles that pit environmentalists and others against so-called “green energy” projects President Joe Biden’s administration is pushing to help speed the nation’s transition from fossil fuels to renewable energy.

The White House says the mine on the Nevada-Oregon line is critical to ramped up efforts to producing raw materials for electric vehicle batteries.

Critics argue digging for lithium poses the same ecological threats as mining for any other mineral or metal in the biggest gold-mining state in the U.S. They say efforts to downplay potential environmental and cultural impacts amount to “greenwashing,”

“We need truly just and sustainable solutions for the climate crisis, and not be digging ourselves deeper into the biodiversity crisis,” said Greta Anderson, deputy director of the Western Watersheds Project, one of the plaintiffs considering an appeal.

U.S. District Judge Miranda Du in Reno concluded late Monday that the opponents had failed to prove the project the U.S. Bureau of Land Management approved in January 2021 would harm wildlife habitat, degrade groundwater or pollute the air.

She also denied — for the third time — relief sought by Native American tribes who argued it could destroy a nearby sacred site where their ancestors were massacred in 1865.

In her 49-page ruling, Du emphasized deference to a federal agency’s approval of such projects. But she also acknowledged the complexity of laws regulating energy exploration under a recent U.S. appellate court ruling she adopted that could pose new challenges for those staking claims under the Mining Law of 1872.

“While this case encapsulates the tensions among competing interests and policy goals, this order does not somehow pick a winner based on policy considerations,” Du warned in the introduction of her verdict.

Other projects that face legal challenges in U.S. court in Nevada include a proposed lithium mine where a desert wildflower has been declared endangered, and a proposed geothermal power plant on federal land near habitat for an endangered toad.

Last week, General Motors Co. announced it had conditionally agreed to invest $650 million in Lithium Americas in a deal that will give GM exclusive access to the first phase of the Thacker Pass mine 200 miles (321 kilometers) northeast of Reno. The equity investment is contingent on the project clearing the final environmental and legal challenges it faces in federal court.

“The favorable ruling leaves in place the final regulatory approval needed in moving Thacker Pass into construction,” Jonathan Evans, Lithium Americas’ president and CEO, said in a statement Tuesday. The company expects production to begin in the second half of 2026.

Du handed a partial victory to environmentalists in agreeing that the Bureau of Land Management had failed to determine whether the company had valid mining rights on 1,300 acres (526 hectares) adjacent to the mine site where Lithium Nevada intends to bury waste rock.

But she denied the opponents’ request to vacate the agency’s approval of the overall project’s Record of Decision, which would have prohibited any construction from beginning until a new record of decision was issued.

Environmentalists clung to the lone part of her decision favorable to them. That part incorporates a recent ruling by the 9th U.S. Circuit Court of Appeals in a fight over the Mining Law of 1872 in a case in Arizona that could prove more onerous to mining companies that want to dispose of their waste on neighboring federal lands.

The San Francisco-based appellate court upheld an Arizona ruling that the Forest Service lacked authority to approve Rosemont Copper’s plans to dispose of waste rock on land adjacent to the mine it wanted to dig on a national forest southeast of Tucson. The service and the Bureau of Land Management long have interpreted the mining law to convey the same mineral rights to such lands.

“It’s disappointing that the BLM and the Biden Administration can’t see through the greenwashing,” Wildland Defense’s Katie Fite said Tuesday.

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